Someone with a very nicely tuned in grow was selling fantastic Pitbull to Oregon dispensaries back in the medical days. Every few months there was a new batch of the good stuff and it sold very quickly. It had a recognizably attractive look to the final product so when other people's Pitbull started showing up it was easy to tell the difference.
I can only guess that one dude is probably responsible for the rise in popularity of the stuff, so many people must have smoked those nice flowers. We'd sell a pound of grams, eighths and quarters in like 5 days and so would all the other shops that stuff was in. People would drive across town to get it instead of going to their local shop.